Error of vibrometer reading due to its reaction on vibrating surface

Summary

• 1. Real vibrometers of finite mass exert a considerable reaction on the vibrating body. The magnitude of the reaction, and hence the error in the vibrometer readings, increases with frequency. The error is particularly large in measurements of the vibration levels of thin plates or rods by heavy vibrometers.

  The order of magnitude of the error in vibrometer readings due to its reaction on a plate in which flexural waves are being propagated can be determined from the formulas given.

• 2. In measurements of mean vibration levels in a frequency range the error due to the reaction of the vibrometer on the vibrating body is inseparable from the result of the measurements. The magnitude of the error largely depends on the nature of the frequency spectrum of the measured vibrations.